#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> v;
typedef vector<v> vv;
typedef vector<vv> vvv;
typedef pair<ll, ll> p;
typedef vector<p> vp;
typedef vector<vp> vvp;
typedef vector<vvp> vvvp;
typedef pair<ll, p> tri;
typedef vector<tri> vtri;
typedef vector<vtri> vvtri;
typedef vector<vvtri> vvvtri;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;
#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(),(v).end()
const ll INF = 1e18;
const ll mod = 1e9 + 7;
int main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
ll n, q, w;
cin >> n >> q >> w;
vtri edges(n - 1);
for (ll i = 0; i < n - 1; i++)
{
cin >> edges[i].s.f >> edges[i].s.s >> edges[i].f;
edges[i].s.f--; edges[i].s.s--;
}
v weight(n - 1);
for (ll i = 0; i < n - 1; i++) weight[i] = edges[i].f;
multiset<ll,greater<ll>> weights;
for (ll x: weight) weights.insert(x);
ll last = 0;
while (q--)
{
ll d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
weights.erase(weights.find(weight[d]));
weight[d] = e;
weights.insert(weight[d]);
auto ptr = weights.begin();
last = *ptr;
if (n > 2)
{
ptr++;
last += *ptr;
}
cout << last << "\n";
}
return 0;
}
